Conventionally, a method for creating metal ingot by continuous casting of metals such as copper alloy is known. In casting, ingot is obtained by solidifying metal while continuously pouring molten metal into a mold.
One factor that affects the quality of ingot is the mold level (hereinafter referred to as “surface height”) of molten metal within the mold. The fluctuation of molten metal surface height causes the thickness of the chill layer on the surface of the ingot and the size of the metal structure to become unstable. Further, it can also cause casting troubles such as overflowing and run-down of the molten metal. Therefore, it is desirable for the molten metal surface height within the mold to be controlled as constant as possible.
As a means to monitor molten metal surface height within a mold, a method of controlling molten metal surface position along six lines, by importing image of the molten metal surface within the mold using a CCD camera, is known (Patent Document 1).